This invention relates to metallic nanostructures whose structure is controlled during the growth process by controlled reductive deposition of metal within a templating bicelle.
An equimolecular complex between a carboxylic acid and an alkylamine where the number of carbon atoms is greater than or equal to seven is commonly termed a catanionic surfactant. A catanionic surfactant may consist of cationic and anionic surfactants with equal numbers of carbon atoms in their alkyl chains or with unequal numbers of carbon atoms in their alkyl chains. The alkyl portions may be partially or completely fluorinated. In water, these materials can form a variety of phases. A bicelle phase can be formed with an appropriate molar ratio of the anionic and cationic surfactants. More generally, a catanionic surfactant consists of any oppositely charged paired surfactant ions acting as counterions to each other.
An example of a catanionic system is the combination resulting from combining salts of cetyltrimethylammonium (CTA) and perfluorooctanoate (FC7). Jung et al. have discussed the physics determining the equilibrium structural composition of a catanionic solution, “H.-T. Jung, L. Y. Lee, E. W. Kaler, B. Coldren, and J. A. Zasakzinski, “Gaussian curvature and the equilibrium among bilayer cylinders, spheres, and discs,” Proc. Nat. Acad. Sci. Vol. 99 (2002) pp 15318-15322. The nanodisks (bicelles) formed using the bromide salt of CTA (CTAB) and the sodium salt of FC7 were reported to be quite small and relatively monodisperse (35±4 and 33±6 nm) for the CTAB/FC7 ratios forming appreciably numbers of bicellar disks.